The present disclosure relates to a position measurement system and a method for its operation.
A position measurement system is known from DE 10 2008 018 355 A1. The position measurement system is made up of a material measure and a scanning device which are movable relative to one another with respect to a measurement direction. The material measure is furnished with a plurality of markings which are arranged in a row with respect to the measurement direction and which encode a pseudorandom binary sequence (PRBS). The scanning device comprises a transmitter winding arrangement which generates an electromagnetic alternating field. Furthermore, multiple receiver coils are provided which are arranged in a row with respect to the measurement direction. The inductive coupling between the transmitter winding arrangement and the receiver coils is a function of the position of the scanning device with respect to the material measure.
The receiver coils are designed in the form of single coils having a single winding direction. However, one specific embodiment is also described in which differentially interconnected coil pairs are used. Here, two single receiver coils having an opposite winding direction are connected in series, which are essentially subjected to the same alternating field generated by the transmitter winding arrangement.
The disadvantage of the single receiver coils is that their signal has a high offset. That is, the signal changes which are caused by the movement of the position measurement system are small with respect to the average value of the signal, which is referred to as the offset. This makes the signal evaluation considerably more difficult. The coil pairs have a small offset, but they require a large amount of space. It is not possible to implement the targeted division period of the material measure of 1 mm and a correspondingly small division period of the scanning device in an economical manner.